Wiring substrate and gas discharge display device

ABSTRACT

A gas discharge display device comprising a front side substrate having a plurality of first electrodes and a back side substrate having a plurality of second electrodes, wherein at least said first electrodes or second electrodes are formed by wet etching using a resist made of an inorganic material, is excellent in the ability to suppress the breakage of wiring in electrodes.

BACKGROUND OF THE INVENTION

[0001] This invention relates to a wiring substrate comprising a wiringsubstrate with a wiring pattern formed thereon, and a gas dischargedisplay device using the same.

[0002] Gas discharge display devices such as plasma display and the likemake display through a self-luminescence, and therefore arecharacterized in that the field angle is large, the display is easy tosee, the thickness can be lessened, and a large picture plane can berealized. Thus, such gas discharge display devices have become appliedto display devices of information terminal equipments and high-qualitypicture tubes of television. Plasma displays are roughly classified intodirect current driving type and alternate current driving type. Amongthem, the alternate current type of plasma display shows a highluminance owing to the memory action of dielectric layer coveringelectrodes, and its lifetime has reached a practical level throughformation of protective layer. This results in practical application ofplasma displays to video monitors for many uses.

[0003]FIG. 9 is a perspective view illustrating the structure of apractical plasma display panel, wherein the front side substrate 100 isshown apart from the back side substrate 200 for the purpose offacilitating understanding.

[0004] The front side substrate 100 comprises a display electrode 600made of a transparent conductive material such as ITO (indium tinoxide), tin oxide (SnO₂) or the like, a bus electrode 700 made of alow-resistance material, a dielectric layer 800 made of a transparentinsulating material and a protecting layer 900 made of magnesium oxide(MgO) or the like, all being formed on a front side glass substrate 400.

[0005] The back side substrate 200 comprises an address electrode 1000,a barrier rib 1100 and a fluorescent material layer 1200, all formed ona back side glass substrate 500. Although not shown in FIG. 9, adielectric layer 1300 is formed on the address electrode 1000, too.

[0006] By affixing the front side substrate 100 to the back sidesubstrate 200 so that the display electrode 600 makes an approximatelyright angle with the address electrode 1000, a discharge space region300 is formed between the front side substrate 100 and the back glassside substrate 500.

[0007] In this gas discharge display device, an alternate currentvoltage is applied between one pair of display electrodes 600 providedon the front side substrate 100, and a voltage is applied between theaddress electrode 1000 provided on the back side substrate 200 and thedisplay electrode 600, whereby an address discharge is made to occur anda main discharge is generated in a prescribed discharging cell. The maindischarge generates an ultraviolet ray, which induces emission of lightsfrom the red-, green- and blue-color fluorescent materials 1200separately coated on respective discharging cells. A display is made byemission of these lights.

[0008] Examples of such prior gas discharge display devices aredescribed in, for instance, FLAT PANEL DISPLAY 1996 (Edited by NikkeiMicrodevice, 1995), pages 208-215.

[0009] Here, the method for forming the bus electrode 700 carried on thefront side substrate 100 and the address electrode 1000 carried on theback side substrate 200 will be mentioned below in more detail. FIG. 5,8A-80 illustrate an exemplary process for forming address electrode 1000on back side glass substrate 500. Explanation of the process for formingbus electrode 700 carried on front side substrate 100 is omitted,because it can be formed by a similar process.

[0010] First, a Cr/Cu/Cr layer (1000 a-c) for forming address electrode1000 on the back side glass substrate 500 and a resist 2500 for formingthe pattern of address electrode 1000 are successively piledlamination-wise by a film-forming technique such as sputtering,evaporation, spin coating, dry filling, etc. (Step (a), FIG. 8A: Filmforming step). Next, the resist 2500 is exposed to light and developedso as to form a desired pattern of address electrode 1000 (Steps (b) and(c), FIG. 8B and 8C: Photolithographic step). Next, using an etchingsolution for Cr, the Cr layer 1000 a is etched to form the desiredpattern (Step (d), FIG. 8D: Etching step). Next, the exposed anddeveloped resist 2500 is peeled off, and a resist 2500 is again formed(Steps (e) and (f), FIGS. 8E and 8F). The above-mentioned treatments arerepeated for each of Cu layer 1000 b and Cr layer 1000 c (Steps (g) to(o), FIGS. 8G-80). Thus, address electrode 1000 is formed on the backside glass substrate 500.

[0011] The above-mentioned process using an etching solution isgenerally called “wet etching”. In the conventional wet etchingprocesses, the resist 2500 is formed from an organic material.

[0012] Further, in the conventional formation of electrodes by wetetching, a photolithographic step for forming a resist is indispensable.

SUMMARY OF THE INVENTION

[0013] In order to reduce the number of repetition of thephotolithographic steps, the present inventors have studied on atechnique for forming a multi-layered wiring such as those having astructure of Cr layer 1000 a/Cu layer 1000 b/Cr layer 1000 c, etc. byusing only the resist 2500 formed by Steps (a)-(c). This technique maybe realizable if an etching solution capable of selectively etching Crlayer or Cu layer is used. Actually, however, it has experimentally beenrevealed that Cr layers 1000 a and 1000 c are quite readily side-etchedand accuracy of fabrication of the Cr/Cu/Cr layer is quite unstable, sofar as an etching solution giving no damage to alkali-developablereleasable resists is used. If a Cr layer is side-etched, theside-etched portions form gaps, which incurs inclusion of voids andcontaminants such as etching solution. The contaminants cause corrosionand breakage of wiring in the step of firing the dielectric. Occurrenceof breakage in the wiring means existence of wire portions notcontributing to display in a gas discharge display panel, which is afatal problem to a display panel. Since Cr/Cu/Cr layer constitutes awiring of lower resistance as compared with other electrode materials,it is quite useful for large-sized display devices such as gas dischargedisplay panel and the like. But, the same problem as mentioned abovearises also in case of forming a multi-layer wiring such as Cr/Al/Cr bythe method of wet etching.

[0014] Further, if the resist is formed of an organic material, theadhesion between resist and electrode is insufficient, which causescorrosion by etching solution at the resist interface. It has furtherbeen revealed that, in such a resist, extraneous materials and airbubbles are included to cause defects in resist, due to which corrosionand thereby caused breakage of wiring can occur. Further, sinceconventional resists have been formed by a photolithographic process,they are apt to have defects due to extraneous matter. If electrode isformed by wet etching from a resist including defects, the regionscorresponding to the defects are similarly etched, which causes breakageof wiring. These problems arise not only in Cr/Cu/Cr type multi-layerwiring, but also in case of forming a wiring of Al, Ag, Ni, Au, etc. bywet etching.

[0015] As above, in the gas discharge display panels and wiringsubstrates in which electrodes are formed by the conventional wetetching technique, breakage of wiring has readily occurred due toside-etching of electrode and unexpected corrosion. Further, breakage ofwiring due to defects of resist has also been apt to occur.

[0016] It is an object of this invention to suppress the breakage ofwiring in the electrodes formed in wiring substrates and gas dischargedisplay panels. In particular, the object of this invention consists insuppressing the breakage of wiring in the case of forming electrodes bywet etching process.

[0017] In order to achieve the object mentioned above, this inventionforms a resist from an inorganic material in a wet etching process.

[0018] Thus, this invention forms a gas discharge display deviceprovided with a front side substrate having a plurality of firstelectrodes and a back side substrate having a plurality of secondelectrodes, wherein at least the first electrodes or the secondelectrodes are formed from a resist made of an inorganic material by wetetching process.

[0019] Further, this invention forms a gas discharge display deviceprovided with a front side substrate having a plurality of firstelectrodes and a first dielectric layer covering said first electrodes,a back side substrate having a plurality of electrodes and a seconddielectric layer covering said second electrodes and a layer of aninorganic material layer interposed at least between said firstelectrodes and said first dielectric layer or between said secondelectrodes and said second dielectric layer, wherein said firstelectrodes or said second electrodes are formed by wet etching process.

[0020] Since a resist formed in the above-mentioned manner by forming aninorganic material into a film by sputtering or evaporation method hasan increased adhesiveness to electrodes as compared with conventionalresists made of organic material, such a resist is prevented from thecorrosion by etching solution at the resist interface and thereby thebreakage of wiring can be suppressed.

[0021] Further, if an inorganic material is used as resist, such aresist does not require so much consideration for etching damage as inthe use of conventional resists made of organic material, so that anetching solution facilitating the control of etching quantity can beused, and the breakage of wiring due to side etching occurring in theconventional technique can be prevented by the use of inexpensiveinorganic material. That is, as the inorganic material, ITO, SiO₂, Ni—Crand the like can be used, for instance.

[0022] Further, since the inorganic material layer is lessened inreactivity with electrodes and dielectric layer, the inorganic layer maybe made to remain between the electrodes and dielectric layer instead ofreleasing the inorganic layer, and this makes it possible to prevent thecorrosion of electrodes and breakage of wiring due to the reactionbetween electrodes and dielectric layer.

[0023] For forming a resist by the use of an inorganic material layer,any means such as photolithography, blaster, laser and the like may beused.

[0024] In order to achieve the object mentioned above, this inventionforms a resist by means of blaster. Thus, the gas discharge displaydevice of this invention comprises a front side substrate having aplurality of first electrodes and a back side substrate having aplurality of second electrodes, wherein at least said first electrodesor said second electrodes have thereon a material layer formed by meansof blaster and said first electrodes or second electrodes are formedfrom said material layer by wet etching process. In this case, thematerial layer serves as a resist for the first or second electrodes.

[0025] For forming the material layer, it is necessary to form aprotecting layer functioning as a resist for said material layer. Sincethis invention forms the material layer (resist) by means of a blaster,etching solution does not permeate the interface between the protectinglayer and the material layer, which lessens the risk of forming defectsin the material layer (resist). This has made it possible to carry outthe wet etching on a material having only a small number of defects andtherefore to suppress breakage of electrodes. In addition, fabricationof a resist by means of blaster can be achieved in a short period oftime at a low cost.

[0026] It should be additionally noted that, if the material layer isformed by means of laser instead of blaster, the formation of protectinglayer necessary to the blaster process is unnecessary, due to whichelectrodes can be formed without photolithographic process and thereforethe electrode-forming process can naturally be shortened to a greatextent. In such an embodiment, the use of mask for forming an electrodepattern is unnecessary. Further, since in this case the material layer(resist) is formed without photolithographic process, a partial removalof the material layer by means of laser is enough for obtaining adesired pattern, which makes it possible to decrease the number ofdefects in resist extremely.

[0027] In these cases, the material layer (resist) may be made of any oforganic material and inorganic material.

[0028] Further, in the case where blaster is used, the same fabricationas achievable by means of laser can be achieved by throttling thenozzle.

[0029] Moreover, the same processing as in the case of using a laser ispossible even if the material layer (resist) is subjected to mechanicalcutting to obtain a desired electrode pattern.

BRIEF DESCRIPTION OF THE DRAWINGS

[0030] FIGS. 1A-1H are process diagrams illustrating the firstembodiment of this invention.

[0031] FIGS. 2A-2L are process diagrams illustrating the secondembodiment of this invention.

[0032] FIGS. 3A-3G are process diagrams illustrating the thirdembodiment of this invention.

[0033] FIGS. 4A-4E are process diagrams illustrating the fourthembodiment of this invention.

[0034] FIGS. 5A-5D are process diagrams illustrating the fifthembodiment of this invention.

[0035] FIGS. 6A-6E are process diagrams illustrating the sixthembodiment of this invention.

[0036]FIGS. 7A and 7B are sectional views illustrating the gas dischargedisplay device of this invention.

[0037] FIGS. 8A-80 are diagrams illustrating the conventional process.

[0038]FIG. 9 is a sectional view illustrating a conventional gasdischarge display device.

[0039]FIGS. 10A to 10D are process diagrams illustrating the seventhembodiment of the present invention.

[0040]FIGS. 11A to 11D are process diagrams illustrating the eighthembodiment of the present invention.

DETAILED DESCRIPTION OF THE INVENTION

[0041] Embodiments of this invention will be explained below byreferring to the accompanying drawings.

[0042] FIGS. 1A-1H illustrate the first embodiment in which addresselectrodes are formed on a back side substrate.

[0043] In these drawings, 10 is a back side glass substrate, and 11 a,11 b and 11 c are address electrodes in which Cr/Cu/Cr layers aresuccessively laminated. 25 is an inorganic material layer functioning asa resist, and 26 is a photoresist layer for forming a pattern of resist25.

[0044] First, Cr layer 11 c, Cu layer 11 b, Cr layer 11 a and ITO layerfunctioning as an inorganic material layer 25 are successively laminatedby sputtering, and then a dry film resist functioning as photoresist 26is laminated (Step (a), FIG. 1A).

[0045] Subsequently, the photoresist 26 (dry film resist) is exposed tolight and developed so as to give a desired electrode pattern, and thenbaked (Step (b), FIG. 1B).

[0046] Subsequently, a blast treatment using calcium carbonate iscarried out to remove the inorganic material layer 25 (ITO layer) (Steps(c) and (d), FIGS. 1C, 1D). This fabrication of resist by blasttreatment makes it possible to form a pattern having an approximatelysame width as that of resist with a very high accuracy in a very shortperiod of time.

[0047] Subsequently, the photoresist 26 (dry film resist) is peeled off(Step (e), FIG. 1E). It is preferable at this time to wash away thedusts of inorganic material layer (ITO layer) formed upon theabove-mentioned blast treatment.

[0048] Subsequently, Cr layer 11 a is etched with an aqueous solutioncontaining potassium permanganate and sodium metasilicate (Step (f),Fig. 1F). In this case, the above-mentioned inorganic material layer 25(ITO layer) acts as a resist for Cr layer 11 a. The aqueous solutioncontaining potassium permanganate and sodium metasilicate is an alkalineaqueous solution which can etch the Cr layer 11 a, while it scarcelyetches the inorganic material layer 25 (ITO layer) and the Cu layer 11b. Thus, the inorganic material layer 25 (ITO layer) is notsubstantially corroded by the alkaline aqueous solution, and the Crlayer 11 a hardly undergoes side-etching throughout the formation.Further, since the adhesiveness between inorganic material layer 25 (ITOlayer) and Cr layer 11 a is good, the surface of Cr layer 11 a incontact with inorganic material layer 25 (ITO layer) is not corroded.

[0049] Subsequently, Cu layer 11 b is etched with an aqueous solutioncontaining ferric sulfate and sulfuric acid (Step (g), FIG. 1G). In thiscase, the inorganic material layer 25 (ITO layer) and the Cr layer 11 aact as a resist for Cu layer 11 b. The aqueous solution containingferric sulfate and sulfuric acid is an acidic aqueous solution which canetch the Cu layer 11 b, while it hardly etches the inorganic materiallayer 25 (ITO layer) and the Cr layer 11 a. Thus, Cr layer 11 a and Culayer 11 b are scarcely side-etched throughout the formation.

[0050] Subsequently, Cr is again etched with an aqueous solutioncontaining potassium permanganate and sodium metasilicate to form anelectrode wiring having a constitution of Cr/Cu/Cr/ITO (Step (h), FIG.1H).

[0051] By the process mentioned above, there can be obtained anelectrode wiring having a constitution of Cr/Cu/Cr/ITO and includingsuppressed breakage.

[0052] As above, by using inorganic material layer 25 (ITO layer) as aresist, a sufficient adhesiveness can be ensured between inorganicmaterial layer 25 (ITO layer) and Cr layer 11 a, and the corrosion ofelectrodes and breakage of wiring caused by etching solution at theresist interface can be suppressed. Further, the resist defects ofinorganic material layer 25 caused by inclusion of extraneous matter andair bubbles can be lessened, and the corrosion of electrodes andbreakage of wiring caused by etching solution can be suppressed.

[0053] Further, the use of inorganic material layer 25 as a resistbroadens the scope of selection of etching solution, and theside-etching of Cr layers 11 a and 11 c in the conventional techniquecan be suppressed. Further, consideration of the etching damage toresist has become unnecessary.

[0054] Further, the use of blaster such as sandblast and the like inplace of conventional etching solutions makes it possible to suppressthe resist defects in inorganic material layer 25. That is, since thereis no permeation of etching solution through the interface betweenphotoresist 26 and inorganic material layer, the possibility of formingdefects in inorganic material layer 25 (resist) is not great. Bycarrying out a wet etching process using such a inorganic material layer25 (resist) small in the number of defects, the breakage of electrodescan be suppressed.

[0055] Further, in this electrode-forming process, Cr layer is etchedwith an alkaline aqueous solution. In the conventional technique forforming alkali-resistant organic resist by photolithographic process,the developing solution and peeling solution for the organic resist havebeen expensive and have caused environmental pollution. On the otherhand, in the process of this invention employing an inorganic resist,the resist is lessened in reactivity with electrodes and dielectric, andtherefore a step for peeling off the resist is unnecessary and nopeeling solution is needed. Further, since inorganic resist is formed bymeans of blaster in place of photolithographic process, the use ofdeveloper for alkali-resistant organic resist is also unnecessary. Inother words, there is no problem concerning developing solution andpeeling solution for organic resist, unlike in the conventionaltechniques.

[0056] Next, FIGS. 2A-2L illustrate the second embodiment for formingaddress electrodes on a back side substrate.

[0057] In the embodiment of FIG. 1, it has been revealed that a smallquantity of etching solution for Cu layer can remain in the defectiveportions such as pin-holes of inorganic material layer 25 (ITO layer) inthe etching process of Cu layer 11 b to corrode Cu layer in thesubsequent steps. Accordingly, in FIG. 2, electrodes are formed by thefollowing processes.

[0058] First, by the same processes as in FIG. 1, Cr layer 11 a isetched (Steps (a)-(f), FIGS. 2A-2F).

[0059] Subsequently, photoresist 26 (dry film resist) not corroded by anetching solution for Cu is laminated on an inorganic material layer 25(ITO layer) (Step (g), FIG. 2G) and then exposed to light so as to makea pattern covering the inorganic material layer 25 (ITO layer) anddeveloped (Step (h), FIG. 2H). Then, the unexposed portion ofphotoresist 26 (dry film resist) is removed (Step (i), FIG. 2I), and theCu layer 11 b is etched with the same etching solution as in FIG. 1(Step (j), FIG. 2J). Thereafter, the photoresist 26 (dry film resist) ispeeled off (Step(k), FIG. 2K). The subsequent processes are carried outin the same manner as in FIG. 1.

[0060] By the above-mentioned treatment, the etching solution for Cubecomes unable to remain in the defects, such as pin-holes, in theinorganic material layer 25 (ITO layer), by which the corrosion of Culayer in the subsequent steps can be suppressed.

[0061] Next, FIGS. 3A-3G illustrate the third embodiment in whichaddress electrodes are formed on the back side substrate.

[0062] This embodiment is the same as that of FIG. 1, except that theblast treatment using calcium carbonate is carried out not only on theinorganic material layer 25 (ITO layer) but also on the Cr layer 11 a(Step (d), FIG. 3D), and after etching the Cu layer 11 b (Step (e), FIG.3E) the photoresist 26 (dry film resist) is peeled off (Step (f), FIG.3F). Accordingly, the photoresist 26 (dry film resist) is selected frommaterials not etched by the etching solution for Cu layer 11 b.

[0063] In the above-mentioned treatment, the step for etching Cr layer11 a can be eliminated, and the electrode-forming process can besimplified. Further, if the efficiencies of blast process and wetetching process are taken into consideration, it is preferable tofabricate down to the Cr layer 11 a by blast process because of thematerial characteristics of Cu layer 11 b and film thickness thereof. Asabove, an electrode formation by combination of a dry etching methodsuch as blast process and a wet etching method is effective forsimplification of process and prevention of breakage of wiring.

[0064] Next, FIGS. 4A-4E illustrate the fourth embodiment in whichaddress electrodes are formed on a back side substrate.

[0065]FIG. 4 is an example of forming electrodes without usingphotolithographic process.

[0066] First, Cr layer 11 c, Cu layer 11 b, Cr layer 11 a and ITO layerfunctioning as an inorganic material layer 25 are successively formed ona glass substrate 10 by sputtering (Step (a), FIG. 4A).

[0067] Subsequently, the inorganic material layer 25 (ITO layer) isremoved by means of laser so as to give a desired electrode pattern(Step (b), FIG. 4B).

[0068] Thereafter, Cr layer 11 a, Cu layer 11 b and Cr layer 11 c aresuccessively etched in the same manner as in FIG. 1 to form an electrodewiring (Steps (c)-(e), FIGS. 4C-4E).

[0069] As above, a resist can be formed by using a laser, without suchphotolithographic steps as shown in FIGS. 1-3, by which theelectrode-forming process can be simplified greatly. Further, the maskfor forming electrodes becomes unnecessary.

[0070] Since there is no photolithographic process, the resist defectsdue to unexposed portions caused by adhesion of extraneous matter can beeliminated, so that the breakage of wiring at the time of wet etchingcaused by the resist defects can be suppressed. That is to say, anelectrode-forming process resistant to extraneous matter can berealized.

[0071] It is also possible to subject the layers of down to Cr 11 a tolaser fabrication, if desired, as shown in FIG. 3. This method isrealizable as understandable from thickness of Cr layer, and anexperiment has actually proved that a fabrication of high accuracy canbe achieved by this method. The process is as shown in FIGS. 5A-5D.

[0072] It has been revealed that , in the processes of FIGS. 4 and 5, avery small quantity of etching solution for Cu layer 11 b can remain inthe defective portions such as pin-holes of inorganic material layer 25(ITO layer) in the etching process of Cu layer 11 b and this remainingetching solution corrodes the Cu layer in the subsequent steps. In orderto solve this problem, in the embodiment shown by FIGS. 6A-6E,electrodes are formed by the following process. FIG. 6 is explained byimagining the process of FIG. 5.

[0073] First, Cr layer 11 c, Cu layer 11 b and Cr layer 11 a aresuccessively formed on glass substrate 10 by sputtering, after whichthereon are formed an ITO layer functioning as inorganic material layer25 and a resist 27 not corroded by the etching solution for Cu layer 11b (Step (a), FIG. 6A).

[0074] Subsequently, resist 27, inorganic material layer 25 and Cr layer11 a are removed by means of laser so as to give a desired electrodepattern (Step (b), FIG. 6B). Since resist 27 is formed by means of laseras above, there is no need to use such a photosensitive material as usedin conventional photolithographic process as a material of resist 27.

[0075] Subsequently, Cu layer 11 b is etched in the presence of resist27 by the use of an aqueous solution containing ferric sulfate andsulfuric acid (Step (c), FIG. 6C). Since the inorganic material layer 25is covered with resist 27, the inorganic material layer 25 is notreadily corroded.

[0076] Then, the resist 27 is peeled off, and the Cr layer 11 c isetched with an aqueous solution containing potassium permanganate andsodium metasilicate (Step (d), FIG. 6D). If desired, the resist 27 maybe peeled off after Step (e).

[0077] By the above-mentioned process, an electrode wiring having aconstitution of Cr/Cu/Cr/ITO and lessened in the risk of wiring breakagecaused by side-etching can be obtained (Step (e), FIG. 6E).

[0078] After this treatment, no etching solution for Cu remains in theinorganic material layer 25 (ITO layer), and corrosion of Cu layer inthe subsequent steps can be suppressed.

[0079] Next, there is explained an electrode with lower cost by reducingside etching and reducing the number of steps comparing with theabove-mentioned embodiments.

[0080]FIGS. 10A to 10D show the seventh embodiment of the presentinvention wherein the electrode is formed by reducing the number of filmformation by sputtering, etc. and aiming at a lower production cost.

[0081] First, Cr layer 11 c, Cu layer 11 b and an alloy layer of Ni andCr as an inorganic material layer 25 are formed on a glass substrate 10by sputtering (Step (a), FIG. 10A). Since the alloy layer of Ni and Cris used, selective etching of the Cr layer 11 c and Cu layer 11 bbecomes possible in a later step. Further, the alloy layer of Ni and Crcan easily be subjected to laser processing.

[0082] Then, the inorganic material layer 25 (the alloy layer of Ni andCr) is removed by using a laser so as to give a desired electrodepattern (Step (b), FIG. 10B). Needless to say, it is possible to employthe above-mentioned blast treatment.

[0083] Subsequently, the Cu layer 11 b and the Cr layer 11 c are etchedin this order in the same manner as shown in FIG. 3 to form an electrodewiring (Steps (c) and (d), FIGS. 10C and 10D).

[0084] This electrode construction does not require the Cr layer 11 amentioned in the above-mentioned embodiments, and thus can omit the filmforming step of the Cr layer 11 a, resulting in making it possible tofurther reduce the production cost. Further, the electrode comprisingthe Cr layer 11 c, the Cu layer 11 b and the Ni—Cr alloy layer iseffective for preventing wire breaking caused by side etching, as wellas for increasing the adhesiveness between the Cr layer 11 c and thesubstrate 10, making the resistance lower by the Cu layer 11 b, andpreventing the reaction with a dielectric layer (not shown in thedrawing) by the Ni—Cr alloy layer, so that requirements demanded for aplasma display panel can be satisfied. It is possible to use SiO₂, ITOSi, Ni, etc. in place of the Ni—Cr alloy layer.

[0085]FIGS. 11A to 11D show eighth embodiment of the present inventionwherein the electrode is formed by reducing the number of film formationby sputtering, etc. and using a thickened Cr layer as the inorganicmaterial layer 25.

[0086] First, a Cr layer 11 c, a Cu layer 11 b and a thick Cr layerwhich is to become an inorganic material layer 25 are formed in thisorder by sputtering on a glass substrate 10 (Step (a), FIG. 11A). Thethickness of the Cr layer 25 is preferably 3 times or more compared withthe thickness of the Cr layer 11 c, in order to set the processconditions mentioned below easier.

[0087] Then, the thick Cr layer (used as an inorganic material layer 25)is removed using a laser to give a desired electrode pattern (Step (b),FIG. 11B). Needless to say, the blast processing can be used asmentioned in the above-mentioned embodiments.

[0088] Subsequently, the Cu layer 11 b and the Cr layer 11 c are etchedin this order in the same manner as shown in FIG. 3 to form an electrodewiring (steps (c) and (d), FIGS. 11C and 11D).

[0089] In this case, when the Cr layer 11 c is etched, the thick Crlayer (inorganic material layer 25) is also etched to reduce thethickness, but by making the thickness of the thick Cr layer (inorganicmaterial layer 25) sufficiently larger than that of the Cr layer 11 c,it is possible to form an electrode having no problem in reliability.Further, by making the thickness of the thick Cr layer larger, pin holesare hardly formed in the thick Cr layer, resulting in reducing theresidual amount of an etching solution for the surface of the Cu layer11 b. This makes it possible to prevent corrosion of the Cu layer inlater steps due to the remaining etching solution.

[0090] By making the thickness of the Cr layer 25 larger, even if thereis no selectivity for etching of the underlayer Cu layer 11 b and the Crlayer 11 c, the electrode can be formed by a combination of dry etchingsuch as a conventional layer processing and wet etching.

[0091] Next, one example of the gas discharge display panel formed bythe above-mentioned electrode-forming processes will be explained byreferring to FIG. 7.

[0092]FIGS. 7A and 7B illustrate a gas discharge display panel, providedthat FIG. 7A is a sectional view parallel to address electrodes and FIG.7B is a sectional view perpendicular to the address electrodes. Theabove-mentioned electrode-forming processes are applied to both of frontside substrate and back side substrate.

[0093] In these drawings, 10 is a back side glass substrate, 11 is anaddress electrode, 12 is a thin film dielectric layer such as SiO₂, 13is a thick film dielectric layer, 14 is a front side glass substrate, 15is a transparent electrode such as ITO, 16 is a bus electrode such asCr—Cu—Cr, 17 is a thin film dielectric layer such as SiO₂, 18 is a thickfilm dielectric layer, 19 is a protecting film made of, for example,MgO, 20 is a sealing member, 21 is an electrode connected from theexternal circuit, 22 is an anisotropic conductive sheet containingconductive particles, 23 is a partition wall, 24 is a fluorescentmaterial layer, and 25 is an inorganic material layer functioning as aresist at the time of electrode formation.

[0094] A front side substrate can be formed in the following manner.

[0095] First, a transparent electrode 15 is formed on a glass substrate14. The transparent electrode 15 may be formed by any means of wetetching, blaster and laser. The use of laser is preferred from theviewpoint of simplification of the process. Subsequently, a buselectrode 14 is formed on the transparent electrode 15 according to theabove-mentioned electrode-forming process of this invention. At thistime, the above-mentioned inorganic material layer 25 exists on the buselectrode 16. Subsequently, a thin film dielectric layer 17 is formed soas to cover at least the transparent electrode 15 and the bus electrode16. For instance, the thin film dielectric layer 17 is formed on thewhole panel surface. Subsequently, a thick film dielectric layer 18 isformed on the thin film dielectric layer 17 by the thick film printingtechnique. Subsequently, a protecting film 19 made of MgO or the like isformed on the thick film dielectric layer 18 by the technique ofevaporation. In the case of front side substrate, the transparentelectrode 15 is formed under the bus electrode 16, and the transparentelectrode 15 is usually an ITO layer. Accordingly, it is allowable, ifdesired, to form the bus electrode 16 including the transparentelectrode 15 and the inorganic material layer 25 according to a seriesof wet etching processes by applying the electrode-forming process ofthis invention. In this case, ITO/Cr/Cu/Cr/ITO are successively formed,and then Cr/Cu/Cr/ITO functioning as bus electrode 16 is formed by anyof the above-mentioned electrode-forming processes of this invention.Subsequently, a resist capable of making the ITO layer, functioning astransparent electrode 15, into a desired pattern is formed, and the ITOlayer is etched by the use of this resist and then the resist is peeledoff to form a transparent electrode 15 and a bus electrode 16. Theinorganic material layer 25 may be made of SiO₂ or Ni—Cr, if desired.

[0096] On the other hand, a back side substrate is formed in thefollowing manner.

[0097] First, an address electrode 11 is formed on a glass substrate 10according to the electrode-forming process of this invention.Subsequently, a thin film dielectric layer 12 is formed so as to coverat least the address electrode 11. For instance, the thin filmdielectric layer 12 is formed on the whole panel surface. Subsequently,a thick film dielectric layer 13 is formed on the thin film dielectriclayer 12 according to the thick film printing technique. Subsequently,on the thick film dielectric layer 13, a partition wall 23 is formed andfurther a fluorescent material layer 24 is formed thereon by theprinting technique. The partition wall 24 may be formed as stripesparallel to the address electrode or as grids surrounding the displaycell.

[0098] After adjusting the positions of the front side substrate and theback side substrate formed above, they are sealed by means of a sealingmember 21. The atmosphere of the sealed space contains a rare gas. Theelectrode 21 leading to the external circuit is connected via anexternal connection terminal of the front side substrate and ananisotropic conductive sheet of the back side substrate, in order tosimplify the connecting process.

[0099] As above, the inorganic material layer 25 is free from the riskof reaction with address electrode 11, dielectric layer 18, buselectrode 16 and dielectric layer 13, and therefore the inorganicmaterial layer can be left to remain without peeling. This makes itpossible to suppress the reactions between address electrode 11 anddielectric layer 18 and between the bus electrode 16 and the dielectriclayer 13, and thereby to prevent the corrosion of address electrode 11and bus electrode 16. Accordingly, there arises no problem, if the thinfilm dielectric layer 12 is not formed.

[0100] As above, as a result of forming the bus electrode and addresselectrode as a Cr/Cu/Cr/ITO layer or a Cr/Cu/Cr/SiO₂ layer, or aCr/Cu/Cr/Ni—Cr layer, the breakage of wiring due to various causes canbe lessened.

[0101] For further lessening the breakage of wiring, a different resistmay be used in either of Cr layer 11 a, Cu layer 11 b and Cr layer 11 c.Another allowable means for achieving this object is to form theinorganic material layer into a double layer structure having aconstitution of Cr/Cu/Cr/ITO/SiO₂.

[0102] It is needless to say that, in the embodiments described above,the same effect as above can be obtained if the Cr/Cu/Cr electrodewiring is replaced by Cr/Al/Cr, Ag, Ni, Au, Al, etc. That is to say, itis needless to say that the same effect as above can be obtained if thematerials used therein are those satisfying the conditions required of agas discharge display panel. It is also needless to say that theelectrode to be formed is not restricted to the address electrode butthe same effect as above can be obtained by forming the bus electrode ofthe front side substrate as shown in FIG. 7. Further, it is needless tosay that this invention can be applied not only to gas discharge displaypanel but also to all the wiring substrates in which electrodes areformed by wet etching technique.

[0103] It is also needless to say that the corrosion of electrode at theresist interface can be prevented even if neither blaster nor laser isused, so far as the inorganic material layer 25 (resist) is present.Conversely, it is also needless to say that defects of resist can besuppressed even if the resist is not made of an inorganic material, sofar as the resist is formed by means of blaster or laser.

[0104] As above, according to this invention, the breakage of wire inthe electrodes formed in wiring substrate or gas discharge displaydevice can be suppressed. Especially, the breakage of wire occurring inthe case of forming electrodes by wet etching technique can besuppressed.

What is claimed is:
 1. A gas discharge display device comprising a frontside substrate having a plurality of first electrodes and a back sidesubstrate having a plurality of second electrodes, at least said firstelectrodes or said second electrodes being formed from a resist made ofan inorganic material by a wet etching process.
 2. A gas dischargedisplay device according to claim 1, wherein said resist is formed bymeans of blaster.
 3. A gas discharge display device according to claim1, wherein said resist is formed by means of laser.
 4. A gas dischargedisplay device according to claim 1, wherein at least said firstelectrodes or second electrodes are Cr/Cu/Cr layers and said resist andthe uppermost Cr layer of said first electrodes or second electrodes areformed by means of blaster or laser.
 5. A gas discharge display deviceaccording to claim 1, wherein at least said first electrodes or secondelectrodes are Cr/Cu/Cr layers and at least the Cr layers of said firstelectrodes or second electrodes are formed by wet etching using analkaline etching solution.
 6. A gas discharge display device accordingto any of claims 1 to 5, wherein said resist is an inorganic materialhaving at least two layers.
 7. A gas discharge display device accordingto any of claims 1 to 6, wherein said resist is an ITO film or SiO₂, orNi—Cr.
 8. A gas discharge display device comprising: a front sidesubstrate having a plurality of first electrodes and a first dielectriclayer covering said first electrodes, a back side substrate having aplurality of second electrodes and a second dielectric layer coveringsaid second electrodes, and an inorganic material layer interposed atleast between said first electrodes and said first dielectric layer orbetween said second electrode and said second dielectric layer, saidfirst electrodes or said second electrodes being formed by wet etchingusing said inorganic material layer.
 9. A gas discharge display deviceaccording to claim 8, wherein said inorganic material layer is formed bymeans of blaster.
 10. A gas discharge display device according to claim8, wherein said inorganic material layer is formed by means of laser.11. A gas discharge display device according to claim 8, wherein atleast said first electrodes or said second electrodes are Cr/Cu/Crlayers and the uppermost Cr layers of said first electrodes or saidsecond electrodes are formed by means of blaster or laser.
 12. A gasdischarge display device according to claim 8, wherein at least saidfirst electrodes or said second electrodes are Cr/Cu/Cr layers and atleast the Cr layers of said first electrodes or said second electrodesare formed by wet etching using an alkaline etching solution.
 13. A gasdischarge display device according to any of claims 8 to 12, whereinsaid inorganic material layer has at least two layers.
 14. A gasdischarge display device according to any of claims 8 to 13, whereinsaid inorganic material layer is an ITO layer or SiO₂ or Ni—Cr.
 15. Agas discharge display device according to any of claims 8 to 14, whereinat least an insulating material layer is interposed between saidinorganic material layer and said dielectric layer.
 16. A gas dischargedisplay device comprising: a front side substrate having a plurality offirst electrodes, a back side substrate having a plurality of secondelectrodes, and a material layer formed by means of blaster on at leastsaid first electrodes or said second electrodes, said first electrodesor said second electrodes being formed from said material layer by wetetching.
 17. A gas discharge display device comprising: a front sidesubstrate having a plurality of first electrodes, a back side substratehaving a plurality of second electrodes, and a material layer formed bymeans of laser on at least said first electrodes or said secondelectrodes, said first electrodes or said second electrodes being formedfrom said material layer by wet etching.
 18. A wiring substratecomprising a wiring pattern formed by the use of a resist made of aninorganic material.
 19. A wiring substrate comprising a wiring patternformed by the use of a resist formed by means of blaster.
 20. A wiringsubstrate comprising a wiring pattern formed by the use of a resistformed by means of laser.
 21. A gas discharge display device comprising:a front side substrate having a plurality of transparent electrodes andbus electrodes formed on said transparent electrodes, and a back sidesubstrate having a plurality of address electrodes, at least said buselectrodes or said address electrodes being made into Cr/Cu/Cr/ITOlayers, Cr/Cu/Cr/SiO₂ layers, Cr/Cu/Cr/ITO/SiO₂ layers, orCr/Cu/Cr/Ni—Cr layers.